Limit Number user ticket

Hello
Can you explain me my error message do not display please

add_filter( 'wpas_before_submit_new_ticket_checks', 'wpas_limit_concurrently_open_tickets' );
/**
 * Limit the Number of Concurrent Open Tickets
 * 
 * @param bool|WP_Error $go Submission status
 *
 * @return bool|WP_Error
 */
function wpas_limit_concurrently_open_tickets( $go ) {
    var_dump( $go );
    $open_tickets = wpas_get_user_tickets( $user_id, 'open' );
    $close_tickets = wpas_get_user_tickets( $user_id, 'closed' );
    $limit     = 7; // -+
    $count   = count( $open_tickets ) + count( $close_tickets);
    if ( $count >= $limit ) {
        // Make sure $go is not already errored
        if ( ! is_wp_error( $go ) ) {
            $go = new WP_Error();
        }
        // Add a custom error message
        $go->add( 'too_many_open_tickets', sprintf( 'Vous avez %1$d tickets maximum et vous les avez tous utilisés !', $limit, $count ) );
    }
    return $go;
}